I assume by your question you want to know how to change your image size display only on you sketchcrawl post.

Below, I took one of your images you posted.
So you can see the code I put the code in quotes an added a period/dot to the img and/img commands so the code would not execute.
Then I followed this with the unchanged image code as a sample.

I then change the s600 in the code to s320 - this changes the image display size on sketchcrawl to display as 3 20 pixels wide instead of the original 600 pixels wide.
I likewise placed the code in quotes so you can see the change,
Then displayed the image as a sample.